This invention relates generally to an apparatus for delivering defibrillation therapy to a patient. Specifically, this invention relates to external defibrillators, more specifically this invention relates to automatic or semi-automatic external defibrillators (AEDs). Further this invention relates to a defibrillator that is automatically activated or inactivated by, for example, inserting or removing an object, such as a plug or a pin, from a receptacle.
Sudden cardiac death (SCD) is the leading cause of death in the United States. On average, 1000 people per day die; this translates into one death every two minutes. Most SCD is caused by ventricular fibrillation (xe2x80x9cVFxe2x80x9d), in which the heart""s muscle fibers contract without coordination, thereby interrupting normal blood flow to the body. The only effective treatment for VF is electrical defibrillation, which applies an electrical shock to the patient""s heart. The electrical shock clears the heart of the abnormal electrical activity (in a process called xe2x80x9cdefibrillationxe2x80x9d) by depolarizing a critical mass of myocardial cells to allow spontaneous organized myocardial depolarization to resume.
To be effective, the defibrillation shock must be delivered to the patient within minutes of the onset of VF. Studies have shown that defibrillation shocks delivered within one minute after the onset of VF achieves up to a 100% survival rate. However, the survival rate falls to approximately 30% after only 6 minutes. Beyond 12 minutes, the survival rate approaches zero. Importantly, the more time that passes, the longer the brain is deprived of oxygen and the more likely that brain damage will result.
Historically, the size and weight of external defibrillators has limited its utility for rapid response by emergency medical response teams. Traditional manually operated monophasic defibrillators require a high degree of skill to operate and thus are typically reserved to the hospital environment. Automatic and semi-automatic external defibrillators (AEDs) provide on-board algorithms to evaluate the cardiac rhythm; these algorithms enable the device to evaluate the appropriateness of administering defibrillation therapy to a patient. An additional factor that has helped to increase the availability of defibrillators in the field is the use of lower energy therapeutic energy pulses. For example, Gliner et al., U.S. Pat. No. 5,607,454 entitled xe2x80x9cElectrotherapy Method and Apparatusxe2x80x9d and incorporated herein, describes an external defibrillator capable of delivering an impedance compensated biphasic waveform. The use of a biphasic waveform considerably lowers the energy required to defibrillate a patient from the standard 200-300-360J used in monophasic external defibrillators to 150J. This enables the device to achieve a lower weight (4 lbs.) than possible for traditional monophasic devices, which typically weigh in excess of 8 lbs. The advancements taught by Gliner et al. are embodied, for example, in the ForeRunner(copyright) AED and the FR2 AED by Agilent Technologies, Palo Alto, Calif.
Although currently available AEDs are considered to be extremely safe to use and deploy, changes to the human factor designs may further ensure correct usage by a minimally trained, infrequent user particularly when such users are under highly stressed conditions. For example, a serious concern existed over whether minimally trained, infrequent users would be able to correctly apply electrode pads following training. In a study performed by Alidene Doherty and presented at the AHA Annual Scientific Session in Orlando, Fla. (November 1997), Abstract No. 2041, it was noted that six months after training first responders had a 67-90% accuracy rate in placing traditional disposable electrode pads on a patient. However, the study also demonstrated that there was a 100% retention of correct pad placement for the electrode pads taught by U.S. Pat. No. 5,951,598 to Bishay et al. entitled xe2x80x9cElectrode System,xe2x80x9d the specification of which is incorporated herein.
There are remaining issues concerning deployment of defibrillators by first responders. For example, will the first responders recall the correct deployment sequence? The step of calling for emergency services, or xe2x80x9c911,xe2x80x9d is an important step that may be inadvertently skipped when an inexperienced lay responder is responding to an emergency. Another concern relates to the possibility that a lay responder could inadvertently turn off the AED at an inappropriate time during the rescue. As defibrillators, particularly AEDs, become increasingly available, it becomes increasingly important to focus design considerations on the human factors that may lead to errors during actual use.
Thus, what is needed, is a method and apparatus for delivering therapy to a patient that addresses the possibility of human error when the device is deployed by a minimally trained, infrequent user.
A defibrillator is provided that has a housing; a high voltage delivery system comprising an energy source and a switch connecting the energy source to an exterior of the housing of the defibrillator; a controller operably connected to the high voltage delivery system; a receptacle within the housing, accessible from the exterior of the housing; and a removable object within the receptacle which changes the operation mode of the defibrillator upon removal. The receptacle may be an electrode receptacle, or other suitable receptacle. The object may be a pin, plug, electrode connector, or other suitable object. The object may also be connected to the defibrillator by a tether. Removal of the object into the receptacle changes the operation of the defibrillator. For example, the operation mode may change from a sleep mode to an on mode, or an off mode to an on mode. Additionally, the defibrillator may be set-up to begin delivering user instructions when the operation mode is changed to the on mode.
Another defibrillator is provided that has a housing; a high voltage delivery system comprising an energy source and a switch connecting the energy source to an exterior of the housing of the defibrillator; a controller operably connected to the high voltage delivery system; a receptacle within the housing, accessible from the exterior of the housing; and an insertable object that changes the operation mode of the defibrillator upon insertion. The receptacle may be an electrode receptacle, or any other suitable receptacle. The object may be a pin, plug, electrode connector, or any other suitable object. The object may also be connected to the defibrillator by a tether. When the object is inserted, the operation of the defibrillator changes. For example, the operation mode may change from a sleep mode to an on mode, or may change from an off mode to an on mode. When the operation mode is changed, the defibrillator may begin delivering user instructions.
A method of operating a defibrillator is also provided. This method includes removing a removable object from a receptacle in the defibrillator housing; automatically changing the operation mode of the defibrillator in response to the removal of the removable object; and delivering instructions to a user. The method may also include changing the operation mode of the defibrillator from a sleep mode to an on mode, or from an off mode to an on mode.
Another method includes: inserting an insertable object into a receptacle in the defibrillator housing; automatically changing the operation mode of the defibrillator in response to the insertion of the removable object; and delivering instructions to a user. The method may also include changing the operation mode of the defibrillator from a sleep mode to an on mode, or from an off mode to an on mode.